Pump jack



April 4, 1961 Filed April 20. 1959 FIG. I

R. H. DOBBS 2,977,808

PUMP JACK 3 Sheets-Sheet 1 FIG. 2.

INVENTOR RICHARD H. DOBBS ATTURNEY R. H. DOBBS PUMP JACK 3 Sheets-Sheet 2 Filed April 20, 1959 6 5 B lllll PlIl||l|l 9 2 r L IHHHHHHI 1111 3 3 IIII l I |||.|.l ll 5 3 r| l I lulu-Fl, 3 I l l l llL a v llw N 5 B k 7 8 2 m. 9 3 3 6 F r 5 FIG. 4

FIG. 5

IN VEN TOR RICHARD H. DOBBS ATTORNEY April 4, 1961 R. H. DOBBS 2,977,808

PUMP, JACK Filed April 20. 1959 3 Sheets-Sheet 3 INVENTOR R ICHARD H DOBBS FIG. 7 BY ATTOR EY sates 2,977,808 PUMP JACK I Richard H. Dobbs,iP.O. Box 113, Winfield, Kans. Filed Apr. 20, 1 959, Ser. No. 807,621

7 Claims. c 74-37 links of the two chains and is reciprocated vertically as,

it travels with the chains.

A very serious disadvantage of such mechanisms is that the space between the two chains must be clear and unobstructed to permit reciprocation of the crosshead. It follows that the shafts supporting the chain sprockets can be journaled only adjacent the outer surfaces of the sprockets, leaving the inner end of each shaft unsupported. Thus as the weight of the pump rod string is lifted, an extreme bending load is placed on the unsupported ends of the sprocket shafts. This bending load is transmitted to the shaft bearings causing excessive wear, failure, replacement, and consequently short life and high maintenance costs.

Another disadvantage of the double chain type of jack is the, difiiculty of transmitting the same power and speed to both chains simultaneously. crosshead is twisted, which in turn is transmitted as a bending load to the upper end of the pump rod string. Repetition of this causes'rod fatigue and eventual failure.

If one chain lags, the

The invention, together with additional advantages over i previous chain operated jacks, will be more clearly un It is a primary object of my invention to obviate the above described ditficulties and disadvantages inherentin conventional dual chain operatedjacks.

More specifically it is an object to provide a jack which utilizes only a singlechain and sprocket assembly for reciprocating the pump rod string. With such an arrangement the shaft which carries the power transmitting sprocket can be journaled in bearings located on each side of the sprocket. Thus there can be no transmission of unbalanced bending loads to the shaft or its bearings. Furthermore, the use of a single chain assembly, .and the attachment of a single link of the chain to the longitudinal center of a cross bar, the opposite ends of which are positively guided to maintain it in a position normal to chain travel, provides positive balance for the cross bar and thus eliminates the transmission of unbalanced bending loads or side thrust either to the frame of the mechanism or to the pump rod string.

Another object of the invention is to provide a pump jack in which the counterweight for the pump rod string cooperates directly with the cross bar to which the single chain link is attached to transmit reciprocating movement from the single endless chain assembly to the pump rod string, thus eliminating the usual and conventional separate counterweight sprocket and chain connection between the counterweight and the rod string, independent of the cross bar and chain assembly.

derstood when the following description is read in corn nection with the accompanying drawings in which:

Fig. 1 is a side elevation of my pump jack connected to the pump rod string of a well, the near side of the protective housing having been removed for clarity, and the housing wall shownin section;

Fig. 2 is a vertical section taken along the line 2-2 of Fig. l;

Fig. 3 is a transverse section taken in the plane indicated by the line 3--3 of Fig. 1;

Fig. 4 is an enlarged fragmentary side elevation illustrating the manner of connecting a pump rod line to the line lifting cables reciprocated by my jack;

Fig. 5 is a schematic side view, partially in section and partially in phantom, and illustrates the manner in which the vertically disposed single chain assembly transmits reciprocatory motion to the counterweight and itsattached cables, the section being taken in the plane indicated by the line 55 of Fig. 3;

Fig. 6 is an exploded perspective view with parts in section and illustrates in detail a preferred manner of connectingthe counterweight to a link of the weight reciprocating chain; and

Fig. 7 is a fragmentary perspective view showing the front of the housing and its closure plate.

Referring to drawing Figs. 1 and 2, a preferred form of pump jack embodying my invention is shown resting on its own base adjacent a well to be pumped. The well is indicated by productiontubing 10,- and a tubing head 11 through which a pump polish rod 12 is to be reciprocated vertically.

Generally my jack includes a rigid upright skeleton frame 13 of cross braced upright angle iron strips welded or otherwise rigidly secured together; a pair of vertically spaced'and aligned sprockets 14 and 15 mounted on shafts 16-17 which are rotatably supported in journal bearings 18-19 and 2021; an endless chain 22 running over the sprockets; means including a power driven shaft 23, sprockets 24 and 25, and a chain 26, for transmitting rotational power to one of the sprockets 15 to drive chain 22; a counterweight 27 reciprocable vertically in the frame 13 and which is internally tunneled and slotted vertically from end to end, as at 28, 29, 30, 31 and 32, Figs. 2 and 3, to permit it to receive and surround the chain, sprocket, shaft and bearing assembly as it reciprocates between the upper and lower positions in Fig. 5; means including a cross bar 33 journaled at its opposite ends in force transmitting slide blocks 34 and 35, for attaching the counterweight 27 to a single link of the chain 22, as clearly illustrated in Fig. 6, so that the chain is free to travel freely and continuously over its sprocket while simultaneously transmitting positively guided true vertical linear reciprocatory motion to the counterweight; and means for transmitting a periodic lifting force from the counterweight to the polish rod 12. Such means includes a pair of laterally spaced suitably journaled and supported pulleys 36 and 37 (Fig. 2), a pair of cables 38 and 39 strung over the respective pulleys, the cables having corresponding ends firmly secured to opposite sides of the counterweight 27, as at 40 and 41 in Fig; 3, and opposite corresponding ends secured to opposite ends of a crosshead 42 (Fig. 4). The upper end of the polish rod 12 passes through the crosshead 42 midway between the cable connection points, and is provided with a lost motion connection to the crosshead bymeans of a common rod clamp 43.

Referring to Fig. 3, the two interior walls 44 and 45 of counterweight 27 are provided with facing opposed slideways designated in-Fig. 6 by the numerals 46 and 47, these slideways being located along the respective lower edges of the two walls 44 and 45. The lowermost wall of each slideway is formed by a pair of longitudinally disposed rigid metal plates 48 and 49, Fig. 5. These plates are removably secured to the lower edges of the respective walls 44 and 45 by screws or studs, not visible in the drawing.

Slideways 46 and 47 (Fig. 6) receive and guide the lateral movement of slide blocks 34 and 35, respectively. The slide blocks have central apertures 50 and 51 into which are press fitted bearings 52 and 53, which receive and journal the opposite ends of cross bar 33. This cross bar passes through and constitutes a part of one reinforced link 54 of chain 22.

Operation As power is transmitted from driven shaft 23 to lower sprocket 15, chain 22 is moved over its two sprockets.

Referring now to Fig. 5, when the'left hand reach of chain 22 is moving downward the slide blocks 34 and 35 are near the left hand ends of their respective slideways 46 and 47, as shown with the counterweight in position B, and the counterweight is moving downward. As a result lifting force is being applied through cables 38 and 39 and crosshead 42, and the polish rod 12 and its attached pump rod string is being moved upward in a true vertical path.

As the chain link 54 which carries the cross bar 33 approaches a dead center position at the bottom of sprocket 15, the slide blocks move to the right in their slideways across vertical slots 31 and 32 (Fig. 3). As the chain link 54 continues its travel slide blocks 34 and 35 move to the location shown in counterweight position C, and the counterweight continues its guided upward stroke. As the counterweight travels upward cables 38 and 39 permit the polish rod and its string to move downward in the well under their own weight, thus completing the downstroke of the pump plunger.

As the counterweight approaches position A in Fig. the slide blocks again shift to the left hand ends of their slideways as link 54 and cross bar 33 pass around the upper portion of sprocket 14, and the downward travel of the counterweight and the upstroke of the polish rod again begins.

It will be understood by those familiar with this art the length of vertical stroke of the polish rod 12 can be increased or decreased by increasing or decreasing the vertical spacing between sprockets 14 and 15.

Details of construction Figs. 1, 2 and 3 illustrate cooperating means carried by the frame 13 and by the counterweight 27 for guiding the latter in a vertical reciprocatory path which lies in a plane tangent to the peripheries of the pulleys 36 and 37.

As shown in Figs. 3 and 5 outwardly facing channel section vertically disposed slideways 55 and 56 are cast into the opposite end walls of the counterweight.

In corresponding positions a pair of rigid channel section guide strips 57 and 58 are welded throughout their length at spaced points to the cross braces of frame 13 (Fig. 1), as at 5960. The web and adjacent portions of the flanges of these channel strips are received in the slideways 55 and 56 on the counterweight, and serve to positively guide the counterweight in its reciprocating movement.

Figs. 1 and 2 illustrate the entire unit enclosed in a sheet metal housing. At its upper end the housing includes a removable sheet metal cap 61. The housing front wall is offset outward from the base to accommodate the reciprocating polish rod 12. As more clearly shown in Fig. 7 the offset portion is provided with a large opening 62 to accommodate tools for work on the crosshead 42 and to connect and disconnect it from the polish rod 12. A complementally shaped plate 64 normally closes the opening 62, and is held in position on the housing by bolts 63. The lower end of plate 64 is provided with a slot 65 to permit its removal from the housing while the polish rod is connected to the crosshead.

The lower end of the housing is weld sealed to provide a lubricant reservoir. The lubricant thus lubricates the entire jack, including the slide blocks 34 and 35, and cross bar 33, during operation.

Having described the invention with sufficient clarity to enable those familiar with this art to construct and use it, I claim:

1. A pump jack for reciprocating the polish rod of a pump comprising: a rigid elongated upright frame; a single pair of vertically spaced and aligned sprockets journaled in said frame; an endless chain engaged with said sprockets; means for transmitting a rotational force to one of said sprockets; a counterweight encompassing said chain and reciprocable vertically therealong; means connecting one link of said chain to the counterweight to reciprocate the counterweight as the chain runs over its sprockets; and means connected to the counterweight and to the polish rod for transmitting a vertical lifting force to the polish rod each time the counterweight is moved downward during its reciprocating motion.

2. The pump jack described in claim 1 and cooperating means carried by the frame and by the counterweight for guiding the latter in a substantially vertical path parallel to the path of travel of the polish rod.

3. The pump jack described in claim 1 in which the means for transmitting a lifting force to the polish rod includes a pulley journaled at the upper end of the frame, and a cable running over the pulley and having one end connected to the counterweight and its other end connected to the polish rod.

4. The pump jack described in claim 3, and means for positively guiding the counterweight during its reciprocation to maintain it in a linear path substantially tangent to the periphery of said pulley.

5. In a pump jack, a rigid elongated frame; a counterweight reciprocable linearly in said frame and having a chain receiving tunnel therethrough extending parallel to its path of reciprocation; oppositely disposed parallel transverse slideways in opposite walls of said tunnel; a slide block in each of said slideways; a pair of chain sprockets journaled in said frame to rotate in a common plane which passes centrally through said tunnel between said slideways; a chain engaged over said sprockets, both reaches of said chain being disposed within said tunnel; a crossbar having its opposite ends journaled in the respective slide blocks, and having an intermediate portion connected to a link of said chain; and means for transmitting a rotative force to one of said sprockets to move the chain, whereby the said chain link, the crossbar and the slides transmit reciprocatory movement to the counterweight as the chain is moved over its sprockets.

6. The pump jack described in claim 5, and means for connecting the counterweight to the plunger rod of a pump to be actuated.

7. In a pump jack, a rigid, elongated frame; a counterweight reciprocable linearly in said frame and having a chain-receiving tunnel therethrough extending parallel to the path of reciprocation of said counterweight; said counterweight being substantially symmetrical in transverse cross section, and having peripheral outside walls and having in its interior a pair of spaced parallel inside walls both extending parallel to the path of reciprocation of said counterweight, said walls having interruptions adjacent the transverse centerlines thereof respectively; oppositely disposed parallel transverse slideways in the inside faces of the opposite inside walls of said counterweight; a slide block in each of said slideways; a pair of spaced, aligned, downwardly extending upper bearings mounted in said frame, an upper shaft carried for rotation by said bearings, an upper sprocket mounted on said shaft intermediate said upper bearings, a pair of spaced, aligned, upwardly extending lower bearings mounted in said frame, a lower shaft carried for rotation by said lower bearings,

a lower sprocket mounted on said lower shaft intermediate said lower bearings, said sprockets being disposed in a common plane which passes centrally through said tunnel between the inside walls of said counterweight, a chain engaged over said sprockets, both reaches of said chain being disposed within said tunnel between said inside walls; a crossbar having its opposite ends journaled in the respective slide blocks, and having an intermediate portion connected to a link of said chain; and means for transmitting a rotative force to one of said sprockets to move the chain, whereby the said chain link, the crossbar, and slide transmit reciprocatory movement to the counterweight as the chain is moved over its sprockets, and whereby at the ends of the travel of the'counterweight the inside walls in the counterweight pass between the respective bearings and adjacent sprockets, the respective shafts are received into the respective interruptions in the inside walls, the bearings are received respectively into the openings in said counterweight between the inside and outside walls thereof, and the sprockets are received respectively into the opening between the inside walls thereof.

8. The pump jack as described in claim 7, and means for connecting the counterweight to the plunger rod of a pump to be actuated.

9. A pump jack for reciprocating the polish rod of a pump comprising: a rigid elongated upright frame; a pair of vertically spaced shafts each having its opposite end journalled in the upright frame; a single sprocket intermediate the ends of each of said shafts, said sprockets lying in a common vertical plane; an endless chain engaged over said sprockets; drive means for rotating one of said sprockets; an internally tunneled counterweight encompassing both reaches of said endless chain and vertically reciprocable from one end to the other of the path described by said endless chain; means interconnecting said chain and the counterweight for vertically reciprocating the tunneled counterweight from one end to the other of the path of said endless chain as said chain moves over the sprockets, said tunneled counterweight alternately encompassing the opposite journalled ends of each of the pair of shafts and their associated sprockets as said tunneled counterweight moves vertically from one end to the other of the path of said chain; and means interconnecting the tunneled counterweight and the polish rod for transmitting a vertical lifting force to the polish rod each time the tunneled counterweight moves downward during its vertical reciprocation.

10. A pump jack for reciprocating the polish rod of a pump comprising: a rigid elongated upright frame; a pair of vertically spaced shafts each having its opposite end journalled in the upright frame; a single sprocket intermediate the ends of each of said shafts, said sprockets lying in a common vertical plane; an endless chain engaged over said sprockets; drive means for rotating one of said sprockets; an. internally tunneled counterweight encompassing both reaches of said endless chain and verticaily reciprocable from one end to the other of the path described by said endless chain; means connected intermediate its ends to said chain and extending transversely thereof in opposite directions perpendicular to the plane of the sprockets and connected for transverse slidable movement to respectively adjacent portions of said tunneled counterweight for vertically reciprocating the tunneled counterweight from one end to the other of the path of said endless chain as said chain moves over the sprockets, said tunneled counterweight alternately encompassing the opposite journalled ends of each of the pair of shafts and their associated sprockets as said tunneled counterweights move vertically from one end to the other of the path of said chain; and means interconnecting the tunneled counterweight and the polish rod for transmitting a vertical lifting force to the polish rod each time the tunneled counterweight moves downward during its vertical reciprocation.

References Cited in the file of this patent UNITED STATES PATENTS 915,181 Huse Mar. 16, 1909 933,904 Huse "Sept. 14, 1909 1,128,545 Swanson Feb. 16, 1915 1,787,164 Parkin Dec. 30, 1930 1,827,959 Stahelin Oct. 20, 1931 1,970,620 Park Aug. 21, 1934 2,309,578 Drachman I an. 26, 1943 

